When video images are presented on an electronic display, just as in film, images are displayed as frames. The refresh rate of a display, that is, the number of times the actual screen image is completely reconstructed every second, tends to be relatively high because more frequently refreshing the screen (display) creates a smoother perceived video image in terms of motion rendering and flicker reduction.
Refresh rates of televisions and other types of video displays are measured in “Hz” (Hertz). For example, a display that has a typical 60 hz refresh rate represents complete reconstruction of the screen image 60 times every second. However, in the present day, it is typical for digital media such as digital video to be recorded at a native frame rate for that digital medium that is different than a refresh rate for a display device that presents the content of the digital medium during playback. As a result, this means that each video frame for a digital medium that has a native frame rate of 24 frames/sec, for example, is repeated more than once on a display that employs a typical refresh rate. This is evident from the fact that the screen image on the display is updated every 16.6 msec (=1/(60 refresh/sec)) for a 60 Hz refresh rate, while a new image of the digital medium is only uploaded to the display once every 41.6 msec (=1/(24 frames/second)).
In other words, although displays may employ refresh rates that are 60 Hz or higher, there are still only 24 separate frames of the digital medium that are displayed every second, which may need to be displayed multiple times, depending on the refresh rate of the display.
Typically, present day displays such as a liquid crystal display (LCD), plasma display, cathode ray tube, light emitting diode display or other display may have a refresh rate of 60 Hz, 72 Hz, 120 Hz, or other refresh rate that is greater than the native frame rate as in the above-illustrated example. In order to accommodate the difference between the native frame rate of the medium whose visual content is to be viewed and the frame refresh rate of the display to present the visual content, present day techniques employ a complex set of operations. In typical implementations multiple redundant memory reads and writes are performed as frame data is moved from a graphics processor to display electronics, which may require translator functionality from display engine to the memory and from display engine to the display panel. A timing controller (TCON) may be located on the display panel, which additionally performs another translator function to reformat pixel information to drive the display panel's row/column drivers.
In one example, during streaming of content, such as DVD content, graphics logic in a graphics processor or part of a central processing unit may render a new image and write it into the system memory. Subsequently, a translation function may be performed when a display engine reads the content from memory and prepares pixel packets to be ready for transmission to an LCD panel for display of the DVD video content. Upon reception of the pixel packets by the timing controller (TCON) on the LCD panel, another translation function is performed to readjust the pixel values to meet the LCD panel requirements and reform for transmission on an internal bus (typically mini LVDS) to the row/column drivers. This partition between graphics and display may serve some systems adequately, for example, a system that includes a desktop computing device motherboard and an external monitor, but may incur undesirable redundancy and inefficiency for display of video content on other devices such as mobile computing devices. This redundancy and inefficiency may especially be evident from a power consumption perspective, because devices including central processing units (CPU), graphics processing units (GPU) and display interface devices consume an undesirable amount of power to perform the above operations.
Accordingly, there may be a need for improved techniques and apparatus to solve these and other problems.